Photographic emulsion



may also he produced by a Patented June 29, 1943 I rnoro ammo Emulsion Hans ill-ens, Dessau,

Walter, and Gustav line & Film Corporation, corporation of Delaware No Drawing. I Application rial No. 368,854. 1939 and Karl Kumetat, Robert Wilmanns, Woll'en, Kreis Bitterfeld, Germany, assignors to General Ani- New York, N.i Y., a

December 6, 1940, Se-

In Germany December 7,

7 Claims. (01. 95-3) Our present invention relates to a photographic emulsion and more particularly to a light sensitive emulsion layer capable of yielding a direct positive.

It is known to incorporate sensitizers into photographic emulsions capable of yielding direct positives by exposure and development. By these sensitizers the sensitivity to light of the emulsions is greatly increased in the range of the long wave rays, but the intrinsic sensitivity thereof is often lowered in the range of short wave length. Moreover, it has been observed that in sensitizing an ordinary photographic emulsion the decrease of its intrinsic sensitivity is especially remarkable if the sensitizer isadded in to ordinary emulsions extent, but are capable of improving the gradation curve. Further sensitizers only slightly increase the sensitivity, but yield a very favourable reversal gradation curve. The choice of the sensitizers therefore depends upon their intended and phthalein dyestuffs.

are capable of absorbing the light to which they render the emulsions sensitive, i. e. they have the property of filter dyes. I

Our present invention has as an object to provide a photographic emulsion directly yielding a positive image and possessing a high total sensitlvity Further objects will be apparent from the following description.

These objects are accomplished by adding a great amount of a sensitizer to an emulsion suitable for the direct production of positivesby exposure and development. By this addition the intrinsic sensitivity of the emulsion is not reduced but considerably increased. Moreover, even the total sensitivity-of the emulsion is enhanced by this means which was not to be ex- Such an emulsion (direct"positive may,

emulsion) for instance, be prepared by incorporating Y into a silver halide emulsion a. substance which rays in the manner described in British Patent No. 443,245 or by a treatment with ultraviolet, visible or infra-red scribed in German Patent No.

693,917. All lames of the rays in the manner as de- The quantities of the sensitizer-s to he used in the present invention amolmt to a multiple of the quantity normally added (about 20-40 mg. for

1 kilo of-emulsion) especially to more than mg. for 1 kilo of emulsion. The optimum quan-' tity generally about -250 mg. for 1 kilo of emulsion must be tested in each case.

The following examples illustrate the invention, but they are not intended to limit it thereto. The direct positive emulsions used in the examples have been prepared in the manner described in U. S. P. No. 2,005,837. The non-sensitized "direct positive emulsion has the sensitivity of l (23). By adding a normal amount of sensitizer the sensitivity of the direct positive emulsion is raised to 2 -2 i. e. the increased fourfold to eightfold.

mgrs. of a dyestufi corresponding the following formula are added:

m0 H.100 0 HI. H: Lcn=cn-cn=i 051:: t me The dyestufi has been prepared inthemanner as described in U. S. P. N0. 2,080,551.

Increase of sensitivity: 2

' "Example 2 "direct positive suitable compounds are mgrs. of a dyestufl corresponding with the folmgrs. of a dyestuff according to the following lowing formula are added: formula are added:

Se OCH, E L H300 e-cni N 0'1 H36 0 l /N n cn=on-cn= 03H. I CzHs /N\ I; The dyestutI has been prepared in the manner v I as described in U. s. P. No. 2,0523% in. Increase of sensitivity: 2 Example 3 Increase of sensitivity: 2". I

To one kilo of a "direct positive emulsion 150 The dyestu disclosed in Examples 4 t0 7 were mgrs. of a dyestufi of the following constitution pr p n t e m nn as d s i d in B l ian are added: Patent No. 436,660.

Example 8 l i To 1 kilo of a direct positive" emulsion 125 3,0,0 00, 1, mgrs. of a dyestufl of the following constitution are added: C2115 1 C2115 02115 The dyestufi has been prepared in a manner 1; analogous to that described in French Patent No. 765,724. 7

Increase'of sensitivity: 2 f

' Example 4 C2115 I CoHi To one kilo of a direct positive emulsion 125 Increase of Sensitivity: mgrs. of a dyestufi of the following constitution 30 Example 9 e add (1: ar e H To 1 kilo of a direct positive emulsion 125 f R mgrs. of a dyestufl of the following constitution c-c-Hi C1 are added: C-CH=CHCH=C 3111;

i r -se N-' Cl. on: I OH, ('3-CH=CHCH= 17 H, /N N HzC.0C.O-(. /Ha CZHS I can Increase of sensitivity: 2 Increase of sensitivity: 2".

Example 5 Example 10 To one kilo Of a d Positive emulsion To 1 kilo of a direct positive" emulsion 125 mgrsbof dyesmfi'of the following constitutmn mgrs. of a dyestuff corresponding to the followare added: ing formula are added:

(1H3 CaHs I CzHs 0-013; t -CH=CH'CH=C CH=CH CH=(IJ /N// N N% \N CH; \1 (EH: (jg/H5 1 11 5 Increa e of sensitivity: 2". HaCOC-O(JH: Example 11 In rease of sensitivit 2 c y To 1 kilo of a direct positive emulsion 125 Example 6 mgrs. of a dyestufi corresponding to the follow- To 1 kilo of a "direct positive emulsion 125 formula e added! mgrs. of a dyestufi corresponding to the follow- 0 (3,116 mg formula are added: N 01 cm 02H:

H Increase of sensitivity: above 2". C I The dyestuffs defined in Examples 8 to 11 were CH: Y produced ina manner analogous to that disclosed in French Patent No. 844,878. Increase of sensitivity: 2 Pmcnaom-rrc-Sansrnzaas Example 7 Example 12 To 1 kilo of a direct positive emulsion 12 To 1 kilo of a direct positive" emulsion 2,823,187 mgrs. of a dyestuif of the following constitution are added: 7

cm on" CH I g V a Rico CGH= I 0GB;

CH=CH CH=(L v \N/ 61 on, Increase of sensitivity: 2 1

Ezample'13 To 1 kilo of a "direct positive emulsion 120 mgrs. of a dyestufl. of the following constitution are added:

\N 01m Increase of sensitivity! 2 Examples 14 to 16 were disclosed in U. S. P. No.

The dyestuffs defined in prepared in the manner The dyestuflsdescribed in Examples 12 and 13 were prepared corresponding to the manner disclosed in German Patent No. 410,487.

} Example 14 To 1 kilo of a direct p ositive mgrs. of a dyestufi emulsion 120 of the following constitution are added:

3 en. S

N N cim JzHs Increase-of sensitivity: 2 Example 15 To one kilo of a direct positive" emulsion 120 mgrs. of a dyestuil corresponding to the following formula are added: V a

Example 16 To 1 kilo oi' a directpositive emulsion 120 formula are added JJIHI Increase of sensitivity: 2

yielding positive images by We claim:

1. A photographic silver halide emulsion fogged to such an extent that it is capable of directly e posure and development and containing at least one sensitizing dyebeing a multiple of the quantity normally used in sensitizing an emulsion but not greater than. approximately 250 fog ng having of said sensitizmg. to 1 kilo of emulsion, said taken place prior to the addition 1 M 2. A photographic silver halide emulsion fogge'd to such an extent that it is capable of directly yielding positive images by exposure and development and containing at least one sensitizing dyestufl in an amount ranging from about 100 to 250 mg. per kilo of emulsion, said fogging having taken place .prior to the addition of said sensitizs dy 3. A photographic material comprising a silver halide emulsion fogged to such an extent that it is capable of directly yielding po itive images by exposure and development and containing at least one sensitizing dyestuif, the quantity of said dyestuif being a multiple of the quantity normally used in sensitizing an emulsion but not greater than approximately 250 mg. to 1 kilo of emulsion, said fogging having taken place prior to the addition of said sensitizing dye.

about 100 to 250 mg. per kilo of emulsion, said fogging having taken place prior to the addition of said sensitizing dye. j

5. A photographic silver halide emulsion fogged to such an extent that it is capable of directly yielding positive images by exposure and development and containing a trimethinecyanine sensi- .tizer with an'imidazole nucleus in an amount ranging from about $0250 mg. per kilo of emulsion, said fogging having taken place prior to the addition of said sensitizing dye.

6. The article as defined in claim 4 wherein the sensitizing dyestuif is orthochromatic.

7. The article as defined in claim 4 wherein the sensiti estufiis anchromatic. sf a dvesmfi corresponding to the following- HANS ARENS.

KARL KUMETAT. ROBERT WALTER. GUSTAV WILMANNS. 

